Two-factor authentication in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the user entered the correct password.

Intro to Computing

if user_input_password == [1]:
    print("Password accepted")

Drag options to blanks, or click blank then click option'

Astored_password

Binput_password

Cuser_password

Dpassword_input

Attempts:

3 left

💡 Hint

Common Mistakes

Using the input variable on both sides of the comparison.

The code compares the entered password with the stored password to verify it.

2fill in blank

medium

Complete the code to send a verification code to the user's phone.

Intro to Computing

send_sms(phone_number, [1])

Drag options to blanks, or click blank then click option'

Aphone_number

Buser_password

Cverification_code

Duser_id

Attempts:

3 left

💡 Hint

Common Mistakes

Sending the password instead of the verification code.

The verification code is sent to the user's phone number for the second authentication step.

3fill in blank

hard

Fix the error in the code that verifies the second factor code.

Intro to Computing

if entered_code == [1]:
    print("Access granted")
else:
    print("Access denied")

Drag options to blanks, or click blank then click option'

Auser_id

Buser_password

Cphone_number

Dverification_code

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing the entered code with the password or phone number.

The entered code must be compared to the verification code sent to the user.

4fill in blank

hard

Fill both blanks to create a dictionary of users with their 2FA status.

Intro to Computing

users_2fa_status = {user: user.[1] for user in user_list if user.[1] [2] "enabled"}

Drag options to blanks, or click blank then click option'

Ais_2fa_enabled

Bnot

Cin

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'in' or 'not' incorrectly in the condition.

The dictionary stores the 2FA status for each user who has 2FA enabled.

5fill in blank

hard

Fill all three blanks to filter users who passed both authentication steps.

Intro to Computing

authenticated_users = {user: status for user, status in users_status.items() if status['password'] [1] True and status['2fa'] [2] True and user [3] blocked_users}

Drag options to blanks, or click blank then click option'

A==

B!=

Cnot in

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'in' instead of 'not in' for blocked users.

The code selects users who have both password and 2FA verified and are not in the blocked users list.

Practice

1. What is the main purpose of two-factor authentication (2FA)?

easy

A. To allow users to log in without any password

B. To make passwords shorter and easier to remember

C. To add an extra layer of security by requiring two ways to prove identity

D. To speed up the login process by skipping verification

Solution

1. Step 1: Understand what 2FA means

   Two-factor authentication means using two different methods to confirm who you are.

2. Step 2: Identify the main goal of 2FA

   The goal is to make it harder for others to access your account by adding extra security.

3. Final Answer:

   To add an extra layer of security by requiring two ways to prove identity -> Option C

4. Quick Check:

   Extra security = To add an extra layer of security by requiring two ways to prove identity [OK]

Hint: 2FA means two ways to prove identity, not shortcuts [OK]

Common Mistakes:

• Thinking 2FA makes passwords shorter
• Believing 2FA removes the need for passwords
• Assuming 2FA speeds up login by skipping steps

2. Which of the following is a correct example of a second factor in two-factor authentication?

easy

A. A code sent to your phone via SMS

B. A password you create

C. Your username

D. Your email address

Solution

1. Step 1: Identify what counts as a second factor

   The second factor is something you have or receive, like a code sent to your phone.

2. Step 2: Compare options to the second factor definition

   A password and username are first factors; a code sent to your phone is a second factor.

3. Final Answer:

   A code sent to your phone via SMS -> Option A

4. Quick Check:

   Second factor = code on phone [OK]

Hint: Second factor is usually a code or device, not password [OK]

Common Mistakes:

• Confusing password as second factor
• Thinking username or email is a second factor
• Ignoring the difference between first and second factors

3. Consider this flowchart for a login process with two-factor authentication:

What happens if the password is correct but the code is wrong?

medium

A. Access is granted immediately

B. Access is denied after code verification fails

C. User is asked to enter the password again

D. User is logged in without code verification

Solution

1. Step 1: Follow the flowchart steps

   The user enters password first; if correct, then code is requested.

2. Step 2: Check what happens if code is wrong

   If the code verification fails, the flowchart shows access is denied.

3. Final Answer:

   Access is denied after code verification fails -> Option B

4. Quick Check:

   Wrong code = access denied [OK]

Hint: Both password and code must be correct to access [OK]

Common Mistakes:

• Assuming password alone grants access
• Thinking user retries password after code fails
• Ignoring the code verification step

4. A user complains they cannot log in even after entering the correct password and code. Which of these is a likely error in the two-factor authentication process?

medium

A. The password was too simple

B. The user entered the wrong username

C. The user did not enter any code

D. The code sent to the user expired before use

Solution

1. Step 1: Analyze the problem with correct password and code

   If the password and code are correct but login fails, the code might have expired.

2. Step 2: Eliminate other options

   Wrong username or no code would cause different errors; password simplicity does not block login.

3. Final Answer:

   The code sent to the user expired before use -> Option D

4. Quick Check:

   Expired code blocks login [OK]

Hint: Expired codes cause login failure despite correct input [OK]

Common Mistakes:

• Blaming password strength for login failure
• Ignoring code expiration time
• Assuming username error when password is correct

5. You want to improve your online account security using two-factor authentication. Which combination below is the best choice?

hard

A. Password + fingerprint scan on your phone

B. Password + security question answer

C. Password + username

D. Password + code sent by email

Solution

1. Step 1: Identify strong second factors

   Biometric methods like fingerprint scans are stronger and harder to fake than codes or questions.

2. Step 2: Compare options for security

   Code by email can be intercepted; username is not a factor; security questions can be guessed.

3. Final Answer:

   Password + fingerprint scan on your phone -> Option A

4. Quick Check:

   Biometric second factor = strongest security [OK]

Hint: Biometrics + password is stronger than codes or questions [OK]

Common Mistakes:

• Thinking username is a second factor
• Believing email codes are always safest
• Underestimating security questions' weakness